1. Field of the Invention
The present invention relates to a honeycomb structure and a manufacturing method of the honeycomb structure, and more particularly, it relates to a honeycomb structure which has an excellent collecting performance of a particulate matter and in which a pressure loss during flowing of a fluid through the honeycomb structure is low, and a manufacturing method of the honeycomb structure.
2. Background Art
In gases discharged from an internal combustion engine such as a diesel engine, various combustion devices, and the like, a large amount of particulate matter (PM) mainly constituted of soot is included. When this PM is discharged to the atmosphere as it is, an environmental pollution is caused. Therefore, in an exhaust system of the discharged gas, a diesel particulate filter (DPF) to collect the PM is disposed.
As this DPF, there has been used, for example, a honeycomb structure “including porous partition walls with which a plurality of cells are formed to become through channels of a fluid (an exhaust gas or a purified gas), and an outer peripheral wall positioned in the outermost periphery”. The honeycomb structure for use as the DPF is a honeycomb structure usually “having plugged portions in open frontal areas of the predetermined cells in an end surface on an inflow side of the fluid (the exhaust gas) and open frontal areas of the remaining cells in the other end surface on an outflow side of the fluid (the purified gas)”.
When the PM in the exhaust gas is collected by using such a honeycomb structure, the PM penetrates into the porous partition walls to close pores of the partition walls, thereby causing the problem that a pressure loss rapidly increases.
To suppress such increase of the pressure loss, a filter has been suggested in which a collecting layer to collect a PM is disposed on the surfaces of partition walls, and the collecting layer prevents the penetration of the PM into the partition walls, thereby suppressing the increase of the pressure loss (see Non-Patent Document 1 and Patent Documents 1 to 3). Moreover, a high-porosity cordierite ceramic filter base material has been suggested in which pores have a spherical shape (e.g., see Non-Patent Document 2).    [Patent Document 1] JP 3750178-B    [Patent Document 2] JP 2926187-B    [Patent Document 3] WO 2008/136232-A